well I had this question earlier this month on the boat I bought- 77 glastron omc drive 4 banger 140 horse. I think it is a 3 litre. At first i thought it was prop. bad news i, I checked compression, 2 and 3 is only 35psi. 1 and 4 is around 120. Wish I would have checked for blow by, dumb mistake, wasn't thinking that night I guess. I adjusted valves,and got a whole 5 psi on the weak ones. I'm thinking it's probably the rings, not to big of deal. Any one got any other ideas I'd appreciate it thanks
